To produce a carbon nanotube device having carbon nanotubes distributed on a substrate, it is necessary to provide metal nanoparticle catalysts on the substrate. Such a technique is disclosed in the following literatures.
Non Patent Literature 1: kinloch, I. A.; Shaffer, M. S. P.; Lam, Y. M.; Windle, A. H. Carbon 2004, 42, 101
Patent Literature 1: Unexamined Japanese Patent Application KOKAI Publication No. 2000-090809
Patent Literature 2: Unexamined Japanese Patent Application KOKAI Publication No. 2003-288835
Conventionally, there are proposed a scheme of disposing metal nanoparticle catalysts made beforehand on a substrate, and a scheme of supporting a catalyst substance on a substrate to spontaneously form a metal nanoparticle catalyst.
The former scheme has an advantage such that the size of the metal nanoparticle catalysts can be controlled according to an objective carbon nanotube, and the latter scheme has an advantage of facilitating catalyst support, so that both schemes are used for the purpose of fabricating a device like a semiconductor device, a field emission display electrode which use carbon nanotubes.
In using the metal nanoparticle catalysts made beforehand, however, there is a problem such that the metal nanoparticle catalysts may cause aggregation and coarsening under a high temperature of synthesizing carbon nanotubes.
The scheme of spontaneously forming the metal nanoparticle catalysts has a problem such that searching of an appropriate support condition of a catalyst is difficult.
On the other hand, [Non Patent Literature 1] discloses that the combinatorial scheme is effective for efficiently searching the support condition of a catalyst.
In any schemes, however, only a part of a metal on the substrate functions as a catalyst, and there is a problem such that lots of catalysts are mixed as impurities in carbon nanotubes.
Accordingly, a technique of efficiently searching a catalyst support condition to form carbon nanotubes on a substrate, and a technique of forming carbon nanotubes that have little amount of catalyst substances mixed as impurities are desired.
Moreover, desired in forming a device is a process for producing a carbon nanotube device which enables fine structure control, and is suitable for the structure of a field emission electron source.
In addition, an important application of carbon nanotubes on a substrate is a field emission electron source used for a display or the like. To that end, it is necessary to control and form the pattern of carbon nanotubes directed in a substrate vertical direction
[Patent Literature 1] discloses a scheme of fixing carbon nanotubes made beforehand at an objective position on a substrate, and [Patent Literature 2] discloses a scheme of depositing catalyst substances at an objective position on a substrate to thereby synthesize carbon nanotubes.
According to the scheme of [Patent Literature 1], however, because the controllability of the direction of the carbon nanotubes which form a pattern is low so that only a part of the carbon nanotubes function as an electrode, and because electrical connection between carbon nanotubes and the substrate is bad, the property of a device is not always good from the standpoint of life duration and power consumption.
On the other hand, according to the scheme of [Patent Literature 2], because carbon nanotubes are uniformly formed on a pattern, electrical field enhancement on the carbon nanotubes is not likely to occur, the extraction voltage is high, only a part of the catalyst substance functions as the catalyst, and impurity mixing in the carbon nanotubes is large.